Question 760033
The circumference of a circle can be calculated as {{{2*pi*radius}}}.
Using the approximation {{{pi=3.14}}}, the circumference of each of those wheels is calculated as
{{{2*3.14*11=69.08}}} inches.
That is how much the car advances as the wheels turn one turn.
In one minute, the wheels go through {{{600}}} turns, so the car advances
{{{600*69.08=41448}}} inches
There are {{{12}}} inches in {{{1}}} foot, so that is
{{{41448/12=3454}}} feet.
There are {{{5280}}} feet in {{{1}}} mile, so that is
{{{3454/5280}}}= approximately {{{0.6542}}} miles.
So, in one minute, the car advances {{{0.6542}}} miles,
and since there are {{{60}}} minutes in {{{1}}} hour, the car's speed is
{{{60*0.6542}}} = approximately {{{highlight(39mph)}}}
 
Writing all the calculations together, we look so much smarter:
{{{(2*3.14*(11inches)/1turn)(600turns/1minute)(1foot/12inches)(1mile/5280feet)(60minutes/1hour)=39.25(mile/hour)}}} = approximately {{{highlight(39mph)}}}
If the teacher expects it, you can write it with the units, as above.
Otherwise, you can write something like
{{{2*3.14*11*600*60/12/5280=39.25}}}
and you can enter all that into a calculator at once as:
2 X 3.14 X 11 X 600 X 60 ÷ 12 ÷ 5280 = 39.25
or as
2 X 3.14 X 11 X 600 X 60 ÷ (12 X 5280) = 39.25